算术指令是执行基本算术运算(例如加法，减法等)的指令。与8085微处理器不同，在8086微处理器中，目标操作数不必是累加器。
下表显示了算术指令列表：
| OPCODE | OPERAND | EXPLANATION | EXAMPLE |
|---|---|---|---|
| ADD | D, S | D = D + S | ADD AX, [2050] |
| ADC | D, S | D = D + S + prev. carry | ADC AX, BX |
| SUB | D, S | D = D – S | SUB AX, [SI] |
| SBB | D, S | D = D – S – prev. carry | SBB [2050], 0050 |
| MUL | 8-bit register | AX = AL * 8-bit reg. | MUL BH |
| MUL | 16-bit register | DX AX = AX * 16-bit reg. | MUL CX |
| IMUL | 8 or 16 bit register | performs signed multiplication | IMUL CX |
| DIV | 8-bit register | AX = AX / 8-bit reg. ; AL = quotient ; AH = remainder | DIV BL |
| DIV | 16-bit register | DX AX / 16-bit reg. ; AX = quotient ; DX = remainder | DIV CX |
| IDIV | 8 or 16 bit register | performs signed division | IDIV BL |
| INC | D | D = D + 1 | INC AX |
| DEC | D | D = D – 1 | DEC [2050] |
| CBW | none | converts signed byte to word | CBW |
| CWD | none | converts signed byte to double word | CWD |
| NEG | D | D = 2’s compliment of D | NEG AL |
| DAA | none | decimal adjust accumulator | DAA |
| DAS | none | decimal adjust accumulator after subtraction | DAS |
| AAA | none | ASCII adjust accumulator after addition | AAA |
| AAS | none | ASCII adjust accumulator after subtraction | AAS |
| AAM | none | ASCII adjust accumulator after multiplication | AAM |
| AAD | none | ASCII adjust accumulator after division | AAD |
D代表目的地，S代表来源。
D和S可以是寄存器，数据或存储器地址。